Vishay, SFH6106-3T DC Input Phototransistor Output Optocoupler, Surface Mount, 4-Pin SMD

The Vishay optocoupler with phototriac output feature a high current transfer ratio, low coupling capacitance and high isolation voltage. These couplers have a GaAs infrared diode emitter, which is optically coupled to a silicon planar phototransistor detector, and is incorporated in a plastic DIP-4 or SMD package. The coupling devices are designed for signal transmission between two electrically separated circuits. The couplers are end-stackable with 2.54 mm spacing.

It has good CTR linearity depending on forward current
It has low saturation voltage, fast switching times